Volume 61, Issue 6

The SARS-CoV-2 infection is characterized by both systemic and organ hyper-thromboinflammation, with a clinical course ranging from mild up-to critical systemic dysfunction and death. In patients with coronavirus disease 2019 (COVID-19) the monocyte/macrophage population is deeply involved as both trigger and target, assuming the value of useful diagnostic/prognostic marker of innate cellular immunity. Several studies correlated morphological and immunophenotypic alterations of circulating monocytes with clinical outcomes in COVID-19 patients, concluding that monocyte distribution width (MDW) may retain clinical value in stratifying the risk of disease worsening. Through an electronic search in Medline and Scopus we performed an updated literature review and meta-analysis aimed to explore the association between increased MDW levels and illness severity in COVID-19 patients, deciphering role(s) and function(s) of monocytes in the harmful network underlining SARS-CoV-2 infection. We found that significantly elevated MDW values were frequently present in COVID-19 patients who developed unfavorable clinical outcomes, compounded by a significant association between monocyte anisocytosis and SARS-CoV-2 outcomes. These findings suggest that blood MDW index and its scatter plot could represent useful routine laboratory tools for early identification of patients at higher risk of unfavorable COVID-19 and for monitoring the progression of viral infection, clinical outcomes, and therapeutic efficacy throughout hospitalization. According to this evidence, therapeutic decisions in patients with SARS-CoV-2 infection could benefit from monitoring MDW value, with administration of drugs limiting thrombo-inflammation due to monocyte hyper-activation in patients with severe/critical COVID-19 disease.

Human pathologies are complex and might benefit from a more holistic diagnostic approach than currently practiced. Omics is a concept in biological research that aims to comprehensively characterize and quantify large numbers of biological molecules in complex samples, e.g., proteins (proteomics), low molecular weight molecules (metabolomics), glycans (glycomics) or amphiphilic molecules (lipidomics). Over the past decades, respective unbiased discovery approaches have been intensively applied to investigate functional physiological and pathophysiological relationships in various research study cohorts. In the context of clinical diagnostics, omics approaches seem to have potential in two main areas: (i) biomarker discovery i.e. identification of individual marker analytes for subsequent translation into diagnostics (as classical target analyses with conventional laboratory techniques), and (ii) the readout of complex, higher-dimensional signatures of diagnostic samples, in particular by means of spectrometric techniques in combination with biomathematical approaches of pattern recognition and artificial intelligence for diagnostic classification. Resulting diagnostic methods could potentially represent a disruptive paradigm shift away from current one-dimensional (i.e., single analyte marker based) laboratory diagnostics. The underlying hypothesis of omics approaches for diagnostics is that complex, multigenic pathologies can be more accurately diagnosed via the readout of “omics-type signatures” than with the current one-dimensional single marker diagnostic procedures. While this is indeed promising, one must realize that the clinical translation of high-dimensional analytical procedures into routine diagnostics brings completely new challenges with respect to long-term reproducibility and analytical standardization, data management, and quality assurance. In this article, the conceivable opportunities and challenges of omics-based laboratory diagnostics are discussed.

Whilst version 2 focussed on the professional conduct expected of a Specialist in Laboratory Medicine, version 3 builds on the responsibilities for ethical conduct from point of planning to point of care. Particular responsibilities that are outlined include: – The need for evidence when planning a new service, providing assurance that a new test does not do harm – Maintaining respect for patient confidentiality, their religious/ethnic beliefs, the need for informed consent to test, agreement on retrospective use of samples as part of governance envelopes in the pre-analytical phase – Ensuring respect for patient autonomy in the response to untoward results generated in the analytical phase – Supporting the safety of patients in the post-analytical phase through knowledge-based interpretation and presentation of results – The duty of candour to disclose and respond to error across the total testing process – Leading initiatives to harmonise and standardise pre-analytical, analytical and post-analytical phases to ensure more consistent clinical decision making with utilisation of demand management to ensure more equitable access to scarce resources – Working with emerging healthcare providers beyond the laboratory to ensure consistent application of high standards of clinical care In identifying opportunities for wider contributions to resolving ethical challenges across healthcare the need is also highlighted for more external quality assurance schemes and ethics-based quality indicators that span the total testing process.

The International Federation of Clinical Chemistry and Laboarator Medicine (IFCC) Committee on Clinical Applications of Cardiac Bio-Markers (C-CB) has provided evidence-based educational resources to aid and improve the understanding of important analytical and clinical aspects of cardiac biomarkers. The present IFCC C-CB educational report focuses on recommendations for appropriate use, analytical performance, and gaps in clinical studies related to the use of cardiac troponin (cTn) by point of care (POC) measurement, often referred to as a point of care testing (POCT). The use of high-sensitivity (hs)-cTn POC devices in accelerated diagnostic protocols used in emergency departments or outpatient clinics investigating acute coronary syndrome has the potential for improved efficacy, reduction of length of stay and reduced costs in the health care system. POCT workflow integration includes location of the instrument, assignment of collection and testing responsibility to (non-lab) staff, instrument maintenance, in-service and recurrent training, quality control, proficiency assessments, discrepant result trapping, and troubleshooting and inventory management.

Objectives This study aims to develop a novel library preparation method, plasma to library express technology (PLET), to construct next-generation sequencing (NGS) libraries directly from plasma without cell-free DNA (cfDNA) isolation. Methods Peripheral blood samples (600) were obtained from a retrospective cohort of 300 pregnant women prior to invasive diagnostic testing. The samples were subsequently distributed between library preparation methodologies, with 300 samples prepared by PLET and 300 by conventional methods for non-invasive prenatal testing (NIPT) to screen for common trisomies using low-pass whole genome next generation sequencing. Results NIPT conducted on PLET libraries demonstrated comparable metrics to libraries prepared using conventional methods, including 100% sensitivity and specificity. Conclusions Our study demonstrates the potential utility of PLET in the clinical setting and highlights its significant advantages, including dramatically reduced process complexity and markedly decreased turnaround time.

Objectives Allogeneic hematopoietic cell transplantation (HCT) is associated with acute graft-vs.-host disease (aGVHD). The presented study applied a novel multiplex antibody-based proximity extension assay (PEA) proteomic platform that can detect thousands of serum proteins simultaneously for the identification of potential biomarkers of aGVHD. Methods Serum samples from 28 patients who underwent allogeneic HCT for acute myeloid leukemia (AML) were analyzed; 17 were diagnosed with grade II–IV aGVHD while 11 patients were not. Samples collected on day −6, day 0, +14, +30, +60 and +90 post-HCT were analyzed for the relative concentrations of 552 proteins. The concentration of each protein from baseline to the closest time point before onset of aGVHD, or to the latest time point in control patients, was documented. Results Individualized analysis identified 26 proteins demonstrating ≥3-fold increase at aGVHD onset compared to baseline, eliminating proteins with a similar increase in controls. Another approach used paired t-testing and logistic regression that identified a four-marker panel, including SLAMF7, IL-1ra, BTN3A2 and DAB2, where individual log-likelihood ratios ranged from 3.99 to 8.15 (logistic regression, p=0.004–0.046). When combined, the four-marker panel demonstrated an area under the curve (AUC) of 0.90 (95% CI: 0.78–1.00; p=0.0006) with high negative predictive value of 81.8% and positive predictive value of 86.7%. All four markers play a physiological role in immune regulation. Among these, three were also present in the individualized analysis (SLAMF7, IL-1ra and BTN3A2). Conclusions We conclude that serum proteins identified using multiplex proteomics, particularly SLAMF7, IL-1ra, BTN3A2 and DAB2, may potentially predict aGVHD.

Objectives Laboratory diagnostic services are essential to drive evidence-based treatment decisions, manage outbreaks, and provide population-level data. Many low- and middle-income countries (LMICs) lack sufficient diagnostic capacity, often further exacerbated in conflict-affected areas. This project assessed laboratory services in conflict-affected LMICs to understand gaps and opportunities for improving laboratory capacity. Methods The World Health Organization Laboratory Assessment Tool Facility Questionnaire (WHO Laboratory Tool) and Stepwise Laboratory Improvement Process Towards Accreditation (SLIPTA) checklist were used to assess five laboratories in Eastern Democratic Republic of the Congo (DRC) and five in Gaza, Palestine. Total scores and percentage outcomes by indicator were calculated. Results Average WHO Laboratory Tool score across all facilities was 41% (range 32–50%) in DRC and 78% (range 72–84%) in Gaza. Lowest scoring indicators in DRC were Biorisk management (13%, range 8–21%), Documentation (14%, range 6–21%), and in Gaza, were Facilities (59%, range 46–75%) and Documentation (60%, range 44–76%). Highest scoring indicators in DRC were Facilities (70%, range 45–83%) and Data and Information Management (61%, range 38–80%), and in Gaza were Data Information and Management (96%) and Public Health Function (91%, range 88–94%). In DRC, no laboratory achieved a SLIPTA star rating. In Gaza, two laboratories had a 3-star SLIPTA rating, one had a 2-star rating and two had a 1-star rating. Conclusions Laboratory systems in conflict-affected LMICs have significant gaps. Implementating improvement strategies in such settings may be especially challenging.

Objectives Hyponatremia is the most frequent electrolyte disorder in hospitalized patients with increased mortality and morbidity. In this study, we evaluated the follow-up diagnostic, the risk of inadequate fast correction and the outcome of patients with profound hyponatremia (pHN), defined as a blood sodium concentration below 120 mmol/L. The aim was to identify a promising approach for a laboratory-based clinical decision support system (CDSS). Methods This retrospective study included 378,980 blood sodium measurements of 83,315 cases at a German tertiary care hospital. Hospitalized cases with pHN (n=211) were categorized into two groups by the time needed for a follow-up measurement to be performed (time to control, TTC) as either <12 h (group 1: “TTC≤12 h”, n=118 cases) or >12 h (group 2: “TTC>12 h”, n=93 cases). Length of hospital stay, sodium level at discharge, ward transfers, correction of hyponatremia, and risk of osmotic demyelination syndrome (ODS) due to inadequate fast correction were evaluated with regard to the TTC of sodium blood concentration. Results pHN was detected in 1,050 measurements (0.3%) in 211 cases. Cases, in which follow-up diagnostics took longer (TTC>12 h), achieved a significantly lower sodium correction during their hospitalization (11.2 vs. 16.7 mmol/L, p<0.001), were discharged more frequently in hyponatremic states (<135 mmol/L; 58 (62.4%) vs. 43 (36.4%), p<0.001) and at lower sodium blood levels (131.2 vs. 135.0 mmol/L, p<0.001). Furthermore, for these patients there was a trend toward an increased length of hospital stay (13.1 vs. 8.5 days, p=0.089), as well as an increased risk of inadequate fast correction (p<0.001). Conclusions Our study shows that less frequent follow-up sodium measurements in pHN are associated with worse outcomes. Patients with a prolonged TTC are at risk of insufficient correction of hyponatremia, reduced sodium values at discharge, and possible overcorrection. Our results suggest that a CDSS that alerts treating physicians when a control time of >12 h is exceeded could improve patient care in the long term. We are initiating a prospective study to investigate the benefits of our self-invented CDSS (www.ampel.care) for patients with pHN.

Objectives Hemolysis, icterus, and lipemia (HIL) are common sources of endogenous interference in clinical laboratory testing. Defining the threshold of interference for immunoassays enables appropriate reporting of their results when they are affected by HIL. Methods Pools of residual patient serum samples were spiked with a known amount of interferent to create samples with varying concentrations of hemolysate, bilirubin, and Intralipid that mimicked the effects of endogenous HIL. Samples were analysed on the Alinity i analyser (Abbott Diagnostics) for more than 25 immunoassays. The average recovery relative to the non-spiked sample was calculated for each interference level and was compared to a predefined allowable bias. Results C-peptide, estradiol, serum folate, free T4, homocysteine, insulin, and vitamin B12 were found to be affected by hemolysis, at hemoglobin concentrations between 0.3 to 20 g/L. Immunoassays for BNP, estradiol, free T3, and homocysteine were affected by icterus at conjugated bilirubin concentrations between 50 to 1,044 μmol/L. BNP, serum folate, and homocysteine were affected by Intralipid with measured triglyceride concentrations between 0.8 to 10 mmol/L. Lastly, serological immunoassays for HIV and hepatitis A, B and C were also affected by interferences. Conclusions Immunoassays are impacted by varying degrees of HIL interference. Some measurands, in the presence of interference, are affected in a manner not previously indicated. The data presented herein provide an independent evaluation of HIL thresholds and will be of aid to resource-limited clinical laboratories that are unable to internally verify endogenous interferences when implementing the Alinity i analyser.

Objectives The aim was to evaluate the stability of serum bicarbonate at room temperature, depending on time to centrifugation and air exposure. Methods Stability study was conducted in the laboratory of Clinical Hospital Centre Rijeka, Croatia in January-February 2022. Nine samples from 10 volunteers were collected in clot activator gel tubes (Greiner Bio-One). Bicarbonate was measured on Beckman Coulter AU480 (Beckman Coulter, Brea, USA). Three tubes were left at room temperature for 30 min, three tubes for 2 h, three tubes for 4 h until centrifugation. First tube from first group (baseline) was measured immediately after centrifugation. Other measurements were expressed as percentage deviation (PD%) from baseline. First tube was remeasured after 1 and 2 h (OT_0h_1h; OT_0h_2h). Second and third tubes were opened 1 and 2 h after centrifugation (C_0h_1h; C_0h_2h). Second group of tubes was processed the same way with 2-hour centrifugation delay (WB_2h; OT_2h_1h; OT_2h_2h; C_2h_1h; C_2h_2h), and third group with 4-hour delay (WB_4h; OT_4h_1h; OT_4h_2h; C_4h_1h; C_4h_2h). PD% was compared to Maximum Permissible Difference (MPD=5.69%). MedCalc statistical software was used (MedCalc, Ostend, Belgium). Results Bicarbonate baseline mean value (range) was 27.3 (23.4–29.6) mmol/L. Obtained PD% (95%CI) were: C_0h_1h 0.46 (−1.21, 2.12); C_0h_2h 0.18 (−2.22, 2.57); OT_0h_1h −6.46 (−7.57, −5.36); OT_0h_2h −10.67 (−12.13, −9.21); WB_2h −0.15 (−2.04, 1.74); C_2h_1h 0.01 (−1.52, 1.54); C_2h_2h −0.40 (−2.65, 1.85); OT_2h_1h −5.43 (−7.30, −3.55); OT_2h_2h −11.32 (−13.57, −9.07); WB_4h −0.85 (−3.28, 1.58); C_4h_1h −2.52 (−4.93, 0.11); C_4h_2h −3.02 (−5.62, 0.43); OT_4h_1h −7.34 (−9.64, −5.05); OT_4h_2h −11.85 (−14.38, −9.33). Conclusions Serum bicarbonate is stable for 4 h in closed uncentrifuged tubes, another 2 h in closed tubes after centrifugation, and is unstable within 1 h in opened tube.

Objectives This study aims to investigate the effect of natural ultralipemic material (NULM) and intravenous lipid emulsion (IVLE) on capillary serum protein electrophoresis (SPEP). Methods NULM material was prepared from leftover patients’ lipemic serum sample (triglyceride concentration >2,000 mg/dL) pool by a refrigerated high-speed centrifuge, and IVLE Omegaven lipid emulsion (30%) was used. Serum pools for interference study were prepared from patient samples for which serum protein electrophoresis was studied as Normal SPEP and M Peak SPEP. For both types of lipemia (DULM and IVLE), five pools with triglyceride concentrations of ∼4.52 mmol/L, ∼7.91 mmol/L, ∼14.69 mmol/L, ∼21.47 mmol/L, and ∼28.25 mmol/L were prepared. SPEP was studied in each pool with Sebia Capillarys Minicap. A repeated measure ANOVA test was used to determine the difference between the pools, and interferograms were used to evaluate the interference effect. Results Interference was not detected in IVLE added Normal SPEP and M Peak SPEP pools, either % or concentrations of fractions. In NULM-added Normal SPEP and M Peak SPEP pools, significant positive interference in albumin % (p=0.002 and p<0.001 respectively) and significant negative interference in gamma% (p<0.001 and p=0.005 respectively) and M protein peak (p=0.002) fractions were detected. However, significant positive interference was seen only for albumin concentration fractions (p<0.001 for both pools). Conclusions It is vital to use NULM instead of IVLE solutions in lipemia interference studies for all laboratory tests, including CZE SPEP. The fractions concentration values calculated with the total protein concentration should be used for evaluating SPEP results.

Objectives Amphotericin B (AmB) is the gold standard for treating invasive fungal infections. New liposomal-containing AmB formulations have been developed to improve efficacy and tolerability. Serum/plasma C-reactive protein (CRP) values are widely used for monitoring infections and inflammation. CRP shows a high affinity to phosphocholine and it aggregates structures bearing this ligand, e.g. phosphocholine-containing liposomes. Therefore, we studied the interaction between CRP and phosphocholine-containing liposomal AmB preparations in vivo and in vitro . Methods CRP was prepared by affinity chromatography. Liposomal AmB (L-AmB, AmBisome ® ) was spiked (final concentrations of L-AmB: 150 mg/L) to CRP-containing serum (final CRP concentration: 300 mg/L). Following the addition of L-AmB, complex formation was monitored turbidimetrically. The size of CRP-L-AmB complexes was assessed using gel filtration. CRP was monitored in patients receiving either L-Amb or AmB lipid complex (ABLC). Results Following addition of L-AmB to CRP-containing plasma, turbidimetry showed an increase in absorbance. These results were confirmed by gel permeation chromatography. Similarly, in vivo effects were observed following intravenous administration of AmBisome ® : a decline in CRP values was observed. In patients receiving L-Amb, decline of CRP concentration was faster than in patients receiving ABLC. Conclusions In vitro experiments are suggestive of a complexation between CRP and liposomes in plasma. Interpretation of CRP values following administration of AmBisome ® might be impaired due to this complexation. In vivo formation of complexes between liposomes and CRP might contribute, or even lead, to intravascular microembolisation. Similar effects have been described following the administration of Intralipid ® and other phosphocholine-containing liposomes.

Objectives Liquid chromatography-tandem mass spectrometry (LC-MS/MS) has become a common technique in clinical laboratories in recent years. Because most methods are laboratory-developed tests (LDTs), their reproducibility and quality control (QC) have been controversial. In this study, Westgard Sigma Rules were used to evaluate the analytical performance and establish an individualised internal QC (IQC) strategy for these LDTs. Methods Taking the LC-MS/MS LDT method for homocysteine (Hcy) as an example, the ‘desirable specifications’ from the Biological Variation Database were used as quality goals. Based on the external quality assessment (EQA) samples, bias was calculated and the coefficient of variation (CV) was also calculated by IQC measurements for six consecutive months. The analytical performance was evaluated by calculated sigma metrics and an IQC strategy was designed using the Westgard Sigma Rules with run size. Results Over 116 days within 6 months, a total of 850 data points were collected for each of IQC 1 and IQC 2. The monthly coefficient of variation CV% was 2.57–4.01%, which was non-significant (p-value: 0.75). The absolute bias% for IQC1 and IQC2 was 1.23 and 1.87%, respectively. The allowable total error (TEa) was selected as 15.5%, Sigma metrics were 4.02 and 4.30, and the analytical performance was ‘Good’. The 1 3s /2 2s /R 4s /4 1s multi rules (n=4, r=1) with a run size of 200 samples were suggested for the Hcy IQC scheme. The quality goal index (QGI) values were over 1.2, indicating that trueness needed to be improved. Conclusions The analytical performance of the Hcy LC-MS/MS LDT conformed to the Six Sigma rating level, achieving ‘good’ (four Sigma). Clinical practice indicated that calibration bias was the primary factor affecting trueness.

Objectives Traditional methods for β-thalassemia screening usually rely on the structural integrity of hemoglobin (Hb), which can be affected by the hemolysis of red blood cells and Hb degradation. Here, we aim to develop a reliable and high throughput method for rapid detection of β-thalassemia using dried blood spots (DBS). Methods Hb components were extracted from a disc (3.2 mm diameter) punched from the DBS samples and digested by trypsin to produce a series of Hb-specific peptides. An analytical system combining high-resolution mass spectrometry and high-performance liquid chromatography was used for biomarker selection. The selected marker peptides were used to calculate delta/beta (δ/β) and beta-mutated/beta (β M /β) globin ratios for disease evaluation. Results Totally, 699 patients and 629 normal individuals, aged 3 days to 89 years, were recruited for method construction. Method assessment showed both the inter-assay and intra-assay relative standard deviation values were less than 10.8%, and the limits of quantitation for the proteo-specific peptides were quite low (1.0–5.0 μg/L). No appreciable matrix effects or carryover rates were observed. The extraction recoveries ranged from 93.8 to 128.7%, and the method was shown to be stable even when the samples were stored for 24 days. Prospective applications of this method in 909 participants also indicated good performance with a sensitivity of 100% and a specificity of 99.6%. Conclusions We have developed a fast, high throughput and reliable method for screening of β-thalassemia and hemoglobinopathy in children and adults, which is expected to be used as a first-line screening assay.

Objectives The primary objective was to determine levels of C3-epi-25(OH)D in very low birth weight infants. The secondary objective was to evaluate the possible influence of preterm birth, intrauterine growth restriction (IUGR), and season of birth on the production of C3-epimers. Methods A total of 127 infants with birth weight less than 1,500 g met the inclusion criteria of the study. We examined 25-hydroxyvitamin-D [25(OH)D] levels and C3-epi-25(OH)D in maternal serum before labor, and in cord blood and infants’ serum on days 14 and 28, and at discharge. Results The mean levels (±SD) of C3-epi-25(OH)D of the cord, on day 14, on day 28, and at discharge were 2.2 (2.9), 7.7 (5.5), 11.7 (7.6) and 14.9 (11.7) nmol/L respectively. The proportion of total 25(OH)D as the C3-epimer was 6.9% (cord), 16.3% (day 14), 22.4% (day 28) and 23.3% (discharge). A statistically significant correlation between 25(OH)D and C3-epi-25(OH)D can be demonstrated from birth. The severity of immaturity and IUGR did not affect the production of C3-epimers. In summer/autumn vs. winter/spring, the mean (SD) percentage of total 25(OH)D as the C3-epimer significantly differs only in maternal serum samples and umbilical cord samples (p value <0.001). Conclusions The production of C3-epi-25(OH)D is functional even in the most immature newborns, has fetal origins, and is largely dependent on circulating 25(OH)D. At the end of the first month of life, C3-epimers make up more than 20% of 25(OH)D.

Objectives Autoantibodies and, specifically antinuclear antibodies (ANA), are the hallmark of systemic autoimmune diseases (AID). In the last decades, there has been great technical development to detect these autoantibodies along with an increased request for this test by clinicians, while the overall pre-test probability has decreased. In this study, we compare the diagnostic performance of three different methods for ANA screening (indirect immunofluorescence [IIF], addressable laser bead immunoassay [ALBIA], and fluorescence enzyme immunoassay [FEIA]). Methods Serum samples at baseline visit from 2,997 participants from the Camargo Cohort, a population with an overall low pre-test probability for systemic AID, were analyzed with the three methods. Participants have a minimum follow-up of 10 years and the development of autoimmune diseases was collected from clinical records. Results The highest frequency of positive ANA was observed by IIF assay. However, ALBIA showed high sensitivity for AID. Likewise, solid phase assays (SPA) presented higher specificity than IIF for AID. ANA prevalence with any method was significantly higher in females and overall increased with age. Triple positivity for ANA was significantly related to the presence of anti-dsDNA–SSA/Ro60, Ro52, SSB/La, RNP, Scl-70, and centromere–specificities. No association was found for anti-Sm – RNP68, or ribosomal P – specificities. Noteworthy, triple positivity for ANA screening was associated with diagnosis of systemic AID both at baseline visit and follow-up. Conclusions ANA detection by IIF may be better when the pre-test probability is high, whereas SPA techniques are more useful in populations with an overall low pre-test probability for systemic AID.

Objectives Marked physiological changes in growth and development present challenges in defining pediatric reference intervals for biomarkers of health and disease. Lambda, Mu, and Sigma (LMS)-based statistical modeling provides a continuous normal distribution by negating skewness and variation, and is commonly used to establish growth charts. Such LMS reference curves are suggested to enhance laboratory test result interpretation. The current study establishes LMS-based continuous reference percentiles for 14 biomarkers in the CALIPER cohort of healthy children and adolescents. Methods Data from healthy children and adolescents aged 1–<19 years were used to establish continuous reference percentiles using a novel LMS-based statistical method, including 2.5th, 25th, 50th, 75th, and 97.5th percentiles. The LMS approach applies a Box-Cox data transformation and summarizes continuous distributions by age via three curves: skewness (Lambda), median (Mu), and coefficient of variation (Sigma). Results LMS-based percentiles and z-scores were generated for 14 common pediatric biomarkers that demonstrate dynamic concentration patterns with age (e.g., alkaline phosphatase) and/or wherein the magnitude of difference from the population mean may be clinically relevant (e.g., triglycerides). The LMS model captured age- and sex-specific distributions accurately and was not substantially influenced by outlying points. Conclusions This is the first study to establish LMS-based continuous reference percentiles for biochemical markers in a healthy Canadian pediatric population. The current LMS-based approach builds upon previous continuous reference interval models by providing graded percentiles to improve test result interpretation, particularly with repeated measures over time. This method may assist in facilitating a patient-centered approach to laboratory medicine.

Objectives Establishing direct reference intervals for pediatric patients is a costly, challenging, and time-consuming enterprise. Indirectly established reference intervals can help to ameliorate this situation. It was our objective to establish population-specific reference intervals for automated white blood cell differentials via data mining and non-parametric percentile method. Methods Blood counts and automated white blood cell differentials of patients aged 0 days to 18 years, performed from the 1st of January 2018 until the 30th of June 2022, were identified in our laboratory information system. Reference intervals were established in accordance with IFCC and CLSI recommendations as well as the propositions by Haeckel et al. Results Initially, 47,173 blood counts on our SYSMEX XN-9000 were identified. 11,707 data sets were excluded, leaving 35,466 sample sets for analysis. Of these, 17,616 contained automated white blood cell differentials. Due to insufficient patient numbers, no reference intervals for automated white blood cell differentials could be established for children aged <7 months. In comparison to the corresponding reference intervals published by Herklotz et al., reference intervals determined by us showed relevant differences throughout all age groups. Conclusions The combination of non-parametric percentile method and the propositions by Haeckel et al. utilizing conscientious data mining appears to be potent alternative to direct reference interval determination.

Objectives To describe a high-sensitivity SARS-CoV-2 antigen test that is based on the fully automated light-initiated chemiluminescent immunoassay (LiCA ® ), and to validate its analytical characteristics and clinical agreement on detecting SARS-CoV-2 infection against the reference molecular test. Methods Analytical performance was validated and detection limits were determined using different types of nucleocapsid protein samples. 798-pair anterior nasal swab specimens were collected from hospitalized patients and asymptomatic screening individuals. Agreement between LiCA ® antigen and real-time reverse transcription polymerase chain reaction (rRT-PCR) was evaluated. Results Repeatability and within-lab precision were 1.6–2.3%. The C 5 ∼C 95 interval was −5.1–4.6% away from C 50 . Detection limits in average (SD) were 325 (±141) U/mL on the national reference panel, 0.07 (±0.04) TCID 50 /mL on active viral cultures, 0.27 (±0.09) pg/mL on recombinant nucleocapsid proteins and 1.07 (±1.01) TCID 50 /mL on inactivated viral suspensions, respectively. LiCA detected a median of 374-fold (IQR 137–643) lower levels of the viral antigen than comparative rapid tests. As reference to the rRT-PCR method, overall sensitivity and specificity were determined to be 97.5% (91.4–99.7%) and 99.9% (99.2–100%), respectively. Total agreement between both methods was 99.6% (98.7–99.9%) with Cohen’s kappa 0.98 (0.96–1). A positive detection rate of 100% (95.4–100%) was obtained as Ct≤37.8. Conclusions The LiCA ® system provides an exceptionally high-sensitivity and fully automated platform for the detection of the SARS-CoV-2 antigen in nasal swabs. The assay may have high potential use for large-scale population screening and surveillance of COVID-19 as an alternative to the rRT-PCR test.